Dynamics of a bacterial DNA uptake machinery

感受态是一种发育状态，其中各种细菌可以从其环境中摄取DNA，并通过同源重组（HR）将DNA整合到其染色体中，从而导致水平基因转移。我们已经发现，在感受态枯草芽孢杆菌细胞中，几种DNA重组蛋白（在生长细胞中DNA修复过程中发挥重要作用）以不同的方式在单个或两个细胞极积累，其中DNA摄取机制组装。不同的Rec蛋白被募集，这取决于是否添加质粒或染色体DNA或噬菌体DNA。HR中的核心参与者RecA在摄取复合物处组装，并形成丝状结构（线程），似乎将传入的DNA引导到染色体上。与重组蛋白相反，摄取复合物是高度静态和稳定的。我们将鉴定感受态复合物的所有组分，并分析取决于添加不同种类DNA的组合物中发生的变化。我们将阐明机器如何在特定的亚细胞位置组装，以及Rec蛋白如何获得新的功能特异性，这取决于将何种类型的DNA添加到细胞中。我们将研究Rec蛋白与Com机制的功能相互作用，并确定如何在分子水平上实现摄取复合物的前所未有的鲁棒性。

Competence is a developmental state in which various species of bacteria can take up DNA from their environment and incorporate the DNA into their chromosome via homologous recombination (HR), leading to horizontal gene transfer. We have found that several DNA recombination proteins (that confer important roles during DNA repair in growing cells) accumulate in a differential manner at a single or both cell poles in competent Bacillus subtilis cells, where the DNA uptake machinery assembles. Different Rec proteins are recruited, dependent on whether plasmid or chromosomal DNA or phage DNA is added. The central player in HR, RecA, assembles at the uptake complex, and forms filamentous structures (threads) that appear to guide incoming DNA to the chromosome. In contrast to recombination proteins, the uptake complex is highly static and stable. We will identify all components of the competence complex and analyse changes occurring in the composition dependent on the addition of different kinds of DNA. We will elucidate how the machinery assembles at a specific subcellular location and how Rec proteins gain novel functional specificity, dependent on what type of DNA is added to the cells. We will study the functional interaction of Rec proteins with the Com machinery and determine how the unprecedented robustness of the uptake complex is achieved at a molecular level.